Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9882228 | Archives of Biochemistry and Biophysics | 2005 | 9 Pages |
Abstract
Dicamba O-demethylase is a multicomponent enzyme that catalyzes the conversion of the herbicide 2-methoxy-3,6-dichlorobenzoic acid (dicamba) to 3,6-dichlorosalicylic acid (DCSA). The three components of the enzyme were purified and characterized. OxygenaseDIC is a homotrimer (α)3 with a subunit molecular mass of approximately 40 kDa. FerredoxinDIC and reductaseDIC are monomers with molecular weights of approximately 14 and 45 kDa, respectively. EPR spectroscopic analysis suggested the presence of a single [2Fe-2S](2+/1+) cluster in ferredoxinDIC and a single Rieske [2Fe-2S](2+; 1+) cluster within oxygenaseDIC. Consistent with the presence of a Rieske iron-sulfur cluster, oxygenaseDIC displayed a high reduction potential of Em,7.0 = â21 mV whereas ferredoxinDIC exhibited a reduction potential of approximately Em,7.0 = â171 mV. Optimal oxygenaseDIC activity in vitro depended on the addition of Fe2+. The identification of formaldehyde and DCSA as reaction products demonstrated that dicamba O-demethylase acts as a monooxygenase. Taken together, these data suggest that oxygenaseDIC is an important new member of the Rieske non-heme iron family of oxygenases.
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Authors
Sarbani Chakraborty, Mark Behrens, Patricia L. Herman, Alexander F. Arendsen, Wilfred R. Hagen, Deborah L. Carlson, Xiao-Zhuo Wang, Donald P. Weeks,